Multi-objective optimization of rotary EDM of aerospace nickel super alloy using Taguchi-entropy weight-based grey relational analysis

Rotary electrical discharge machining (REDM) is a variant of standard die sink EDM, in which the rotary motion is imparted to the electrode to remove the debris effectively. It is known that REDM has conflicting and correlated objectives likeradial overcut (ROC), surface roughness (SR) and metal removal rate (MRR). This study proposes multi-objective optimization of ROC, SR and MRR in REDM of aerospace nickel super alloy using hybrid methodology of Taguchi method, entropy method and grey relational analysis (GRA). The dominant process parameters in REDM like peak current, pulse on time, pulse off time and speed of rotationof electrode are considered for optimization. The experiments are conducted according to Taguchi’s L9orthogonal array. Then a hybrid methodology of Taguchi-entropy weight-based GRA is applied for multi-objective optimization. ANOVA of overall grey relational grade indicates that it has improved by 8.31%. Consequently, ROC, SR & MRR are improved by 13.86%, 14.93% and 6.93% respectively. This resulted in improved quality of components machined by REDM. Confirmatory results prove the potentiality of this hybrid methodology.